I’m an engineer and exhibit developer. I’m prototyping a stepper driver system based on Arduino and your products. I have 15 years experience in exhibits, following 10 years in motion control, robotics and embedded systems.
I am interfacing A4988…
…with the 40 oz*in hybrid…
…according to the information contained on the above two pages, plus the A4988 FAQ page
Below is a schematic of the motor connections I am using. The motor center taps are left out for clarity, they are isolated and capped. The A4988 pin numbers shown are those of a conventional 16 pin IC. I’ve triple checked everything to be sure this is what I think I want, and what I have wired up.
The symptoms I’m getting are: somewhat weak torque; an intermittent tendency to take the first step from rest in the wrong direction; and the effect of microstepping is to reduce the angular speed by the expected ratio when slewing, but maintaining a single step minimum resolution at low speeds… with the big step happening about every nth step pulse. In short, classic symptoms of scrambled phases / coils. The phases look OK on the o-scope, but W/O a logic analyzer (just a 2 channel storage scope) I can’t be sure of phase ID. The motor buzzes out as expected.
Do you see anything I’ve bungled, or is there something off in the documentation? I’ve never had this symptom and NOT immediately found a silly wiring boo-boo… but this one has me stumped.
Thanks, and cheers…